TY  - JOUR
A1  - Belaidi, Houmam
A1  - Rauch, Florian
A1  - Zhang, Zuolun
A1  - Latouche, Camille
A1  - Boucekkine, Abdou
A1  - Marder, Todd B.
A1  - Halet, Jean-Francois
T1  - Insights into the optical properties of triarylboranes with strongly electron-accepting bis(fluoromesityl)boryl groups: when theory meets experiment
JF  - ChemPhotoChem
N2  - The photophysical properties (absorption, fluorescence and phosphorescence) of a series of triarylboranes of the form 4-D-C\(_6\)H\(_4\)-B(Ar)\(_2\) (D=\(^t\)Bu or NPh\(_2\); Ar=mesityl (Mes) or 2,4,6-tris(trifluoromethylphenyl (Fmes)) were analyzed theoretically using state-of-the-art DFT and TD-DFT methods. Simulated emission spectra and computed decay rate constants are in very good agreement with the experimental data. Unrestricted electronic computations including vibronic contributions explain the unusual optical behavior of 4-\(^t\)Bu-C\(_6\)H\(_4\)-B(Fmes)\(_2\) 2, which shows both fluorescence and phosphorescence at nearly identical energies (at 77 K in a frozen glass). Analysis of the main normal modes responsible for the phosphorescence vibrational fine structure indicates that the bulky tert-butyl group tethered to the phenyl ring is strongly involved. Interestingly, in THF solvent, the computed energies of the singlet and triplet excited states are very similar for compound 2 only, which may explain why 2 shows phosphorescence in contrast to the other members of the series.
KW  - boron
KW  - density functional calculations
KW  - luminescence
KW  - phosphorescence
KW  - photophysics
KW  - activated delayes flourescence
KW  - 3-coordinate organoboron compounds
KW  - light-emitting-diodes
KW  - phosphorescene spectra
KW  - molecular structures
KW  - high efficiency
KW  - pi-conjugation
KW  - trivalent boron
KW  - single photon
KW  - donor
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-205600
VL  - 4
IS  - 3
ER  - 
TY  - JOUR
A1  - Kole, Goutam Kumar
A1  - Merz, Julia
A1  - Amar, Anissa
A1  - Fontaine, Bruno
A1  - Boucekkine, Abdou
A1  - Nitsch, Jörn
A1  - Lorenzen, Sabine
A1  - Friedrich, Alexandra
A1  - Krummenacher, Ivo
A1  - Košćak, Marta
A1  - Braunschweig, Holger
A1  - Piantanida, Ivo
A1  - Halet, Jean-François
A1  - Müller-Buschbaum, Klaus
A1  - Marder, Todd B.
T1  - 2- and 2,7-substituted para-N-methylpyridinium pyrenes: syntheses, molecular and electronic structures, photophysical, electrochemical, and spectroelectrochemical properties and binding to double-stranded (ds) DNA
JF  - Chemistry - A European Journal
N2  - Two N-methylpyridinium compounds and analogous N-protonated salts of 2- and 2,7-substituted 4-pyridyl-pyrene compounds were synthesised and their crystal structures, photophysical properties both in solution and in the solid state, electrochemical and spectroelectrochemical properties were studied. Upon methylation or protonation, the emission maxima are significantly bathochromically shifted compared to the neutral compounds, although the absorption maxima remain almost unchanged. As a result, the cationic compounds show very large apparent Stokes shifts of up to 7200 cm\(^{-1}\). The N-methylpyridinium compounds have a single reduction at ca. −1.5 V vs. Fc/Fc\(^+\) in MeCN. While the reduction process was reversible for the 2,7-disubstituted compound, it was irreversible for the mono-substituted one. Experimental findings are complemented by DFT and TD-DFT calculations. Furthermore, the N-methylpyridinium compounds show strong interactions with calf thymus (ct)-DNA, presumably by intercalation, which paves the way for further applications of these multi-functional compounds as potential DNA-bioactive agents.
KW  - inorganic chemistry
KW  - viologens
KW  - chromophores
KW  - luminescent
KW  - pyrenes
KW  - pyridinium
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-256642
VL  - 27
IS  - 8
ER  -